Initially such containers are empty and haphazardly disposed in a container from which they are discharged with their axes disposed horizontally. The containers are then fed forward lying on their sides with their axes transverse to the direction in which they are travelling, their necks being, at random, on either one side or the other of said direction. In this way the containers successively arrive at apparatus which is intended to arrange them with their axes vertical, each with its neck facing upwards.
An entry unit of such apparatus consists of two sets of belts, one above the other, and two lateral guides and conveys the containers downwardly. The containers are gripped between upper and lower branches of the belts of the two sets, which are adjacent and which move in unison at the same speed and each container is constrained between the lateral guides with its neck resting on one of these guides and its body (that is the part between the bottom and shoulders from which the neck of the container projects) against the other.
In apparatus previously known the containers, from such an entry unit, are then carried by a dragging action along two sets of rod-shaped guides, which are specially shaped in substantially helical form and are symmetrical in relation to a vertical longitudinal plane of the apparatus, two of said rod-shaped guides constituting an extension of said two lateral guides. The containers are propelled along these rod-shaped guides by lower branches of two belts, which are symmetrical and adjacent to said longitudinal plane and, like the rod-shaped guides, have a circular cross-section.
Each container is firstly laid on its side and its uppermost side is engaged from above by said two belts. Then, as it slides on said sets of guides, the container is rotated and raised and this uppermost side, depending on which way the neck of said container is pointing, is selectively engaged by the side of one or the other of the two belts. When operating correctly the progressive rotation of the container takes place in vertical planes transverse to the apparatus and in one or other direction, by reason of which the neck of the container assumes an upwardly facing orientation and the side which was originally uppermost moves towards the longitudinal plane and reaches a vertical position.
However, in previously known apparatus it is not uncommon for containers to rotate not only in vertical transverse planes, but also horizontally; this causes obstruction of the apparatus and is mainly attributed to the fact that the transport effected by the two belts is not always positive. The lightness of plastic containers and the presence of dirt on the guides and belts can cause variations in the frictional engagement of the belts and container. It can therefore be seen that this known apparatus is unreliable in operation, especially if it is intended to reach high operating speeds.